During the excavation of tunnels a required number of holes is drilled in the rock, and thereafter the holes are charged with explosives and a planned portion of the rock is blasted from the rock. The tunnel proceeds in “rounds”. In order to properly loosen the rock during blasting along the entire portion of the round and also in order for the tunnel to have a planned profile and direction, the explosive holes must be carefully drilled. A drilling plan is planned in advance for the rounds, where the dimensions and type of rock in the tunnel are taken into account. The drilling plan determines the number, diameter, length and location of the explosive holes on the back wall of the tunnel. A rock drilling apparatus, which comprises a movable base and drilling booms—typically 1 to 6 thereof—arranged onto the base, is used for drilling holes. Each drilling boom comprises a rock drill. The operator of the rock drilling apparatus is able to control the drilling manually, or alternatively the rock, drilling apparatus is provided with a control unit that automatically attends to the movements of the drilling booms and to the drilling operation. In manual drilling, the ability and experience of the operator of the apparatus play an important part when the measures associated with drilling during one round, i.e. the drilling sequence is to be efficiently controlled. Wide experience is generally required before the operator is capable of controlling a rock drilling apparatus to best possible effect taking both the efficiency and quality factors into account. However, great differences may occur among experienced operators in the total time used for drilling a round. Deficiencies have also been detected in connection with the implementation of the drilling sequence of automatically controlled rock drilling apparatuses. Current control systems are not able to control the drilling to best possible effect, and it is typical that some of the drilling units have already finished the provided tasks, whereas other units are still drilling. In such a situation, the drilling units that have finished their work wait until the other units have finished the drilling holes thereof. It is obvious that drilling is not arranged as effectively as possible, if some of the drilling apparatuses remain unused for a long time when drilling a round.